Control System Design Of3-dof Heavy Testing Platform

In order to meet the working requirements of heavy load, instantly enormous impact and complexity of sea waves motion, a new platform based on parallel mechanism is proposed in this reaserch, which achieved high precision, high reliability in real-time tracking.Firstly, this paper analyzed mechanical structure and kinematics characteristics of the heavy swaying testing platform, to provide test data for control system design. Its rocking and rolling station coordination and corresponding mathematical model were illustrated to accomplish parametric modeling and assembly drawings on PROE. Then the virtual simulation model in gravitational field was established on ADAMS based on virtual prototype technology, to achieve relevant test data through kinematical analysis of mechanism.Due to the heavy-weight, great inertia and complex work environment of heavy platform, motor drive mode could hardly be able to meet the requirements, so hydraulic drive mode was chosen on account of its smooth transmission, anti-interference and fast response ability. Hence, this paper established mathematical modeling of hydraulic system, and explained basic principles of computer-controlled hydraulic system. After the simulation analysis of PID control, the sliding mode control based on exponential reaching law was put forward. The simulation results showed that sliding mode control could meet high precision, fast response and robustness when the system was under parameter perturbations, external disturbance, and which would achieve accurate control performance.Finally，the discrete sliding mode control was designed and implemented, which was adapted for computer control, and automatically generated Verilog HDL code on FPGA. Using the Quartus II software and ModelSim simulation tool as development and testing environment, the IP core, namely sliding mode control module was formed eventually on FPGA platform. The sliding mode control module fulfilled the requirement of control system and had certain reliability through co-simulation verification.